Ethylene is oxidized to produce ethylene oxide substantially in the presence of a silver catalyst, with side reactions to generate carbon dioxide, water, etc., wherein activity, selectivity, and stability constitute main performance indexes of the silver catalyst. Activity refers to a reaction temperature required at a certain reaction load in producing ethylene oxide. A lower temperature indicates a higher catalytic activity. Selectivity is the molar ratio of the ethylene which has been converted to ethylene oxide to the total amount of ethylene used in the reaction. And stability represents the decline rate of activity and stability, with a lower decline rate indicating a better stability.
Using a silver catalyst of high activity, high selectivity, and good stability in producing ethylene oxide by oxidation of ethylene can significantly improve economic efficiency. Therefore, it is a major direction in the art to prepare a silver catalyst of higher activity, higher selectivity, and better stability.
An existing method of preparing a silver catalyst comprises two steps: preparing a porous carrier (such as alumina) and adding active components and promoters to the carrier. Some new techniques of preparing silver catalyst carriers have been reported in recent years.